faint white, stinky exhaust with popping sound from a newly rebuilt 400

[jdscofield]

Hey Guys,

I have a fresh (less than 100 miles) rebuilt 400 in my charger.  recently i noticed i can see the exhaust coming from the tail pipes.  nothing major, more like what it would look like on a cold day.  trouble is, its not cold.  Also, there is a popping sound which seems like its coming from the mufflers.  the engine seems not to be idling fast enough to me.  when i pull the manual choke half way out, it seems to idle fine and i no longer hear the popping sound, but i still smell the exhaust and see a little smoke.  could the smoke be from the engine not completely broke in yet?  Thanks for any input

[c00nhunterjoe]

Sounds like unburnt fuel. Half closing the choke to make it run decent tells me you have carb issues to tune.

[firefighter3931]

Sounds like unburnt fuel. Half closing the choke to make it run decent tells me you have carb issues to tune.

Good observations 

(1) retarded timing will send unburnt fuel into the exhaust which will ignite when it hits the hot pipes causing "popping"

(2) lean mixture will also result in the same thing commonly referred to a "lean pop"



Ron